Propeller inhibitor



Patented June 13, 194.4

PROPELLER INHIBITOR Theodore F. W. Meyer, Birmingham, Mich., as-

signor to Federal-Mogul Corporation, Detroit, Mich., a corporation of Michigan Application December 24, 1943, Serial No. 515,547

7 Claims.

` This invention relates to an improved construction and assembly of propeller inhibitors for the purpose of maintaining a sound electrical contact between the inhibitor and the propeller, and has for its object the attainment of such a permanent electrical contact of minimum resistance between the two that the seepage of water between the thus associated parts, which would of course diminish or possibly break down the desired completeness of contact, is prevented.

As is well known, the immersion in Salt water and in close juxtaposition of two metal articles, even metals of such cognate character as cast iron and steel respectively, paves the way for the setting up of an electric current flow between them. An example of this would even be a steel engine shaft on which is mounted a cast iron propeller; and if, with a steel engine shaft, there is associated a brass or bronze propeller wheel, the generated or transmitted current when the two are immersed in salt water would be correspondingly greater In the securing of as tight a mechanical iit as possible between the shaft and the hub of the wheel, resort has long been had to the tapering of each member, so that, when the tapered hub of the propeller wheel is driven onto the tapered shaft end, an at least initially adequate electrical contact is had betweenthe two members. But in time a certain seepage of salt water into the circular line of contact between them at their outer ends develops, thus causing the formation by corrosion of a film between the shaft and wheel hub, and thus creating resistance to an electric current flow between them.

For protection from this, the inhibitor here shown is in the form of a cap over the otherwise exposed line of contact between the shaft end and the propeller wheel hub; But unless this inhibitor cap be kept in similar close electrical contact with the shaft upon which it is potentially mounted, it fans of its inhibiting action.

The purpose of this invention, therefore is to provide an inhibitor construction whose contact with the propeller shaft is so fluid-tight that a permanent electrical contact of minimum resistance is maintained between these parts, while still making possible the quick removal or replacement of the inhibitor without dismantlement of the propeller.

In the drawing:

Figure 1 is a longitudinal section showing a portion of the propeller shaft and a small portion of the propeller hub, the inhibitor being shown in longitudinal central section;

Figure 2 is a partly sectional elevational view taken along the line 2-2 of Figure 1 and looking in the direction of the arrows there shown, with the specially formed washer element shown in elevational relation thereto in full lines.

YFigure 3 is a sectional elevational view taken along the line 3-3 of Figure 1 and looking in the direction of the arrows there shown.

Figure 4 is a sectional elevational View taken along the line 4 4 of Figure 1 and looking in the direction of the arrows there shown.

Figure 5 is a sectional elevational View taken along the angularly correlated lines 5-5 of Figure 1, and looking in the direction of the arrows there shown.

At I0 is shown the end of a propeller shaft which, as usual, is slightly tapered as at Illa, t0 permit the driving thereon of the correspondingly tapered central bore in the hub ll of the propeller, care being taken that the t be as accurate as. possible, so that there will be a minimum of electrical resistance to the passage of such currents from one part to the other as either may be generated galvanically by the immersion of the propeller and the shaft in salt water, or may be extraneously injected or induced into the propeller shaft.

In the case of a new installation, the propeller shaft I0 is fabricated in the beginning with integral and coaxial extension portions 2| and 22, the extreme outer end of the latter one of which, 22, projects beyond the closure piece 25 over the outer end of the inhibitor cap 2D, so that the compressing or assembly nut 26 can ride on the threaded end thereof, as will be hereinafter further explained. If, however, it is desired to secure the benefits of my disclosed inhibitor cap assembly for an already-existing shaft and propeller wheel installation, the rst extension section 2l is threadly installed in a correspondingly threaded bore 2|a in the end of the propeller shaft I0; and similarly, into the end of this extension 2| there is fitted one end of the second extension section 22; and on the end of this latter which extends beyond the end of the inhibitor cap 20 and through the terminal closure piece 25 rides the nut 26 already mentioned.

In either case, the purpose of these shaft extension parts is to provide a coaxially positioned '56 medium upon and about which the inhibitor cap 20 is centered, and which being structurally and electrically unitary with the shaft I0, can, if sufciently closely associated with the tapered in- ,5 A terior portion of the inhibitor cap 20, partake of sirk all of the current-transmitting characteristics of ner wrench. Between the active or (as viewed in Figure 1) left-hand face of this nut I3 and the adjacent face of the propeller hubis positioned ya suitable gasket lock-washer I5, preferably of such soft or pliable material as soft Monel metal,

which is provided with a single initially bent-over tongue I4 which is adapted, upon the described positioning of the gasket lock-washer I5, to engage in the recess I Ib in the propeller hub. Any one of the tongues I5a, |5h, |5c, I5d or I5e is adapted to be bent up, as shown at |5a inFigure 1, according to which one of them will most accurately and anchoringly interengage with the milling on the periphery of the nut I3 as it is turned to force the lock-washer I5 tightly against the propeller hub II, and thus hold the nut against unseating rotativemovement.

The preferred contour of the gasket washer I5 is shown elevationally in Figures 2 and 3, the tongue I4 thereof being, as explained above, preformed to fit into the hole IIb in the propeller hub. There are also provided a plurality of tongues as |5a, I5b, |50, |5d, and I5@ which in the gasket as furnished lie in the plane thereof. Any one of these tongues is adapted for turning up into such one of the peripheral slots |3c in the nut I3 as the attained position of the gasket vwhen forced against the propeller hub by the action of the nut I3 makes possible. In other words, with such a slight rotational turning one way or thelotherof the gasket as may be necessary, some one of these tongues may be placed in registry with'some one of the Vperipheral slots |30. And it will be noted that the'side faces of each'of these tongues 15a, I 5b, I5c, I5d and I5e are slightly inclined toward each other as in crosssectionally truncated conical form so as to afford a clearance of about 2,to allow Vfor taperV variations. Between the Vthus arranged tongues there arelpositioned about the periphery of the gasket washer I5 the dummy or non-functioning tongues |5f, which flank the illustrated position of the overbent tongue I4, and also a larger dummy peripheral portion I 5g, which is positi'oned not quite diametr'ically opposite tothe tongue I and the dummy tongues |5f just mentioned. I. Y y I, v l

The corrosive seepage of wateralfong and into thethreading ofthe nut I3 would, in due time, occur if the structure thus far described were left unprovided with the water-iight inhibitor cap 20. This cap has a skirt portion as 29o, which is adapted to fit over thev wrench-hold portion of the nut I3 and is centrally bored throughout its length for lthe engagementtherethough of the shaft extensionsZI and 22. The intermediate portion of the inhibitor cap is taperingbf bored so as to i'ltv tightly' over and about'the correspondingly tapered .peripheral surface of the' shaft `extension 2|. Thev farthest .outf extension 22 ofthe shaft projects beyond thend ofthe cap and through aterminal piece 25 vwhich is contoured or .beveledtovt tightly over the corre-v spondingly contoured end of the inhibitor cap. Against it rides a compressing nut 26.

It will be noted that the skirt portion 20a of the inhibitor cap is spaced from the adjacent shoulder and wing portion of the nut I3, to permit of possible Variances in the degree to which the inhibitor cap 2B is forced inwardly upon the tapered periphery of the shaft extension 22, by the compressive action of the nut 26 upon the threaded end of this shaft extension. The interior of the inhibitor is further selectively contoured as at 21a to permit the positioning therewithin of a compressible washer or gasket 2l; as the inhibitor cap is driven down upon the shaft extension 22 this gasket or washer is compressed to a degree suicient to render the line of contact between it and the shaft and the nut I3 water-tight.

Similarly, near its outer end the inhibitor cap 20 is recessed as at 28a to permit the positioning of a washer 28 about the shaft extension 22, this washer being similarly compressible by the action of the nut 26 upon the shaft 22; this renders the potential line of contact between the end surface Zille of the inhibitor cap and the correspondingly bevelled or inclined surface 25a of the terminal closure piece 25 water-tight, so that the access of water to the cap-enclosed shaft portions from that direction is prevented.

Thus, due to the attained tightness of fit of the tapered interior `bore of the inhibitor cap 20 and of the correspondinglyy tapered surface of the shaft extension 2|, an effective seal is provided against the access of water which would set up or facilitate a galvanic or transmitted action between the propeller hub and the shaft. The described parts, however, are capable of easy removal without unshipping the propeller II from the shaft I0. It is thus an easy matter to effect the replacement of the inhibitor in case it has become impaired by the action of sea water, or has become externally damaged, without unshipping of the propeller from its hub; and the quick and effective positioning of a substitute inhibitor cap is thus made easy with the assurance that, clue to its compressive action upon the washer pieces 27 and 25, the seepage of water into and about the propeller shaft extension will be prevented.

I claim: Y

1; An inhibitor for a marine propeller installation designed to be maintained in permanent electrical contact therewith, consisting of a cap projecting beyond the propeller-carrying end of the shaft thereof, said cap being provided with an inner shoulder, a gasket between said shoulder and tlieouter end of said nut, a shaft extension extending axially through said cap and threadedat its outer end to receive a second nut', a washer tted over the end of said cap, a gas-` ket between said cap and washer and adapted tof seal rthe opening `through which saidextension passes, and a nut on the end of the extensionwherebylto maintain said cap in position.

VAn ,inhibitor for preventing the access of waterbetweena propeller wheel and the shaft whereon said' .propeller-wheel ris mounted, comprising, in combination with a, terminally threadedextension of said shaft,'a.centrally bored cap member adaptedto fit tightlyoverl an intermediate portion of said shaft extension, compressible washer members positionedlwithin said cap member on either side of the intermediate portion ofsaid shaft extension'ovef which the cap engages,a nut-riding on the-threaded'outer end of said shaft', extension .for exerting a compressive action on the included parts lengthwise of said shaft extension, a gasket washer positioned about the propeller wheel shaft between the propeller wheel hub and the securing nut therefor, `a selected peripheral portion of said gasket washer being adapted to be bent to interlocking position relatively to the propeller wheel hub, and a nut riding on the threaded end portion of said shaft extension which is nearest the propeller hub, whereby said gasket washer may be forced thereagainst, and with a selected peripheral portion of which a then adjacently positioned peripheral projection of said gasket washer is adapted to be interlocked.

3. In combination with a propeller shaft, a propeller wheel mounted thereon, and an outwardly projecting shaft extension which is threaded at each of its end portions, means for protecting the line of contact between said propeller shaft and its supported wheel against the acn cess of a potentially corrosive fluid, comprising a cap member engaging about said shaft extension, a pair of compressible Washer members spacedly positioned along said propeller shaft extension, a nut on the outer end of said propeller shaft extension whereby the cap and its included parts may be compressed axially lengthwise of the propeller shaft extension to effect the uid excluding compression of said washer members, a nut riding on the threaded end of said o shaft extension nearest the propeller wheel, and a gasket Washer adapted to be forced against the propeller wheel hub by action of this lastnamed nut, said gasket Washer being provided with a plurality of peripherally disposed tongues by the bending of selected ones of which into engagement with suitably recessed portions of the propeller Wheel hub and of its holding nut respectively the gasket washer may be locked in its attained position relatively thereto.

4. Means for protecting a propeller wheel and its supporting shaft against the seepage of water into and along their line of contact, comprising, in combination with a terminally threaded extension of said shaft, a cap engaging axially thereabout, a gasket washer positioned on said supporting shaft immediately adjacent said propeller wheel, said gasket washer being provided with a plurality of peripherally arranged projections one of which is overbent to interlockingly engage the hub of the propeller wheel, a nut riding on a threaded portion of said shaft extension in position to force said gasket washer against the propeller hub, the peripheral portion of said nut being adapted to be engaged by a bent-up one of the other peripheral projections on the gasket washer to effect their interlocked enga-gement, a pair of compressible gasket members spacedly positioned lalong said shaft extension operatively Iadjacent either end of the cap, one of said gaskets engaging against the top portion of said last-mentioned nut, and a compression nut riding on the outer end of said shaft extension, wherebyr the recited parts may be forced into watertight propinquity.

5. Means for inhibiting the access of a potentially corrosive fluid to the line of contact between a propeller wheel and its supporting shaft, comprising, in combination with a coaxially disposed extension thereof provided with selectively positioned threaded portions, a gasketI washer provided with selectively positioned peripheral projections one of which is adapted to be bent to position of interlocking engagement with the hub of the propeller wheel, a nut riding on that threaded portion of said shaft extension nearest the propeller wheel and adapted to force said gasket washer thereagainst, some peripheral portion of said nut being adapted to be engaged by some one of the then overbent peripheral pro- Jections on said gasket washer, a centrally bored inhibitor cap engaging about said shaft extension, a plurality of compressible washers positioned about said shaft extension and included within said inhibitor cap, one face of one of said washer members engaging against the top face of said nut, a closure piece for the end of said inhibitor cap against which the other of said compressible washers engages, and a compression nut riding on the outer threaded end of said shaft extension whereby the inhibitor cap and its included parts may be forced lengthwise of said shaft extension into 'water-tight relation.

6. In combination with a longitudinally extended propeller shaft and with a propeller wheel mounted on the non-extended portion thereof, the hub of said propeller Wheel being provided with a selectively positioned recess, `a, gasket washer provided with a plurality of selectively positioned peripheral projections, one of which is adapted to anchoringly engage in the recess in the propeller Wheel hub, a nut for forcing said gasket Washer against the propeller hub, its periphery being adapted to be lockingly engaged by some one of the other peripheral projections on said gasket washer, an inhibitor cap positioned over the extension portion of said propeller shaft, a compressible washer member disposed between the top of said nut and an interiorly shouldered portion of said inhibitor cap, a second compressible Washer positioned about said shaft and against the outer end of said cap, a centrally apertured closure piece carried on said shaft beyond the end of the cap, and a nut riding on the threaded outer end of the shaft extension whereby the inhibitor capand its included parts are held in water-excluding relation about said shaft extension.

'7. An inhibitor installation for a marine propeller which is held on its terminally threaded shaft by means lof a nut riding thereon, consisting of a cap overengaging said nut and provided with an inner shoulder, a gasket positioned loe-V tween said shoulder and said nut, a terminally threaded shaft extension passing coaxially through said cap, a threaded nut riding thereon whereby said cap is held in position on the propeller shaft, and sealing means interposed between the cap and said last mentioned nut.

THEODORE F. W. MEYER. 

